*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
html , body{
    height: 100%;
    background-image: url(../pic/背景.jpg);
    background-position:center;
    background-repeat: no-repeat;
    background-size: cover;
}

.nav{
    height: 50px;
    background-color: rgb(50, 50, 50);
    line-height: 50px;
    color: rgb(163, 189, 198);
    padding-left: 50px;
}
.container{
    width: 100%;
    height: calc(100% - 50px);

    display: flex;
    align-items: center;
    justify-content: center;
}